1. Field of the Invention
The present invention relates to hydrodynamic clutch devices and more particularly to a hydrodynamic clutch device having a transmission.
2. Description of the Related Art
DE 44 23 640 A1 describes, particularly in FIG. 1, a hydrodynamic clutch device in the form of a torque converter having a clutch housing which can be brought into working connection with a drive, for example, the crankshaft of an internal combustion engine. The torque converter has an impeller wheel, a turbine wheel and stator wheel axially arranged between the impeller wheel and the turbine wheel thereby forming a hydrodynamic circuit, wherein the stator wheel is arranged on a stator freewheel.
The above-mentioned working connection between the drive and a clutch housing can be seen, for example, from DE 32 22 119 C1, FIG. 1. In this case, where the crankshaft serves as a drive, the clutch housing is screwed thereto via a plate. Consequently, because of the fixed connection with respect to rotation, the rate of rotation of the clutch housing corresponds to the rate of rotation of the crankshaft. When the clutch housing is also constructed in one piece with the impeller shell of the impeller wheel, as is the case in DE 44 23 640 A1, the impeller wheel also adopts the rate of rotation of the crankshaft accordingly.
The acceptance torque of a clutch device of the type mentioned above must be adapted to the torque characteristic of the drive. In this connection, the clutch device must be designed such that its characteristic is flexible or smooth enough that it does not cause the drive to stall during cold starting of diesel engines which are especially critical in this respect. The drawback in adapting the clutch device in this way is a comparatively poor efficiency because, due to the unchangeability of the characteristic of the clutch device, it must also be maintained when the drive is at warm operating temperature.
Different constructions have been suggested to solve this problem. For example, DE 195 29 739 A1 suggests a second turbine wheel which can be switched on via a clutch so that a second characteristic can be realized. However, a construction of this kind is very complicated and expensive.